Test for whether permission should be given to adduce expert evidence
The appellant appealed against a deputy master's decision refusing permission for it to call expert evidence.
Warren J held that the deputy master had erred in finding that because the judge would be able to decide a matter without expert evidence, the judge would not be assisted by it. That was not the correct approach: if the evidence might be helpful, the court should determine whether it falls within CPR r35.1, which provides that "expert evidence shall be restricted to that which is reasonably required to resolve the proceedings". The judge laid down the following test:
- Looking at each pleaded issue, is it necessary to have expert evidence to resolve that issue? If so, expert evidence must be admitted.
- If, however, the evidence is not necessary, would it still be of assistance to the court in resolving that issue? If so, the court can determine the issue without the evidence.
- The next question is then whether, in the context of the proceedings as a whole, expert evidence on that issue is reasonably required to resolve the proceedings. In deciding this, the court will take into account factors such as the value of the claim, the effect of a judgment either way on the parties, who will pay for the expert evidence and any delay which the evidence would entail (especially if a trial date will have to be vacated).
The judge added that: "although CPR 35.1 does not refer to issues, but only to proceedings, if evidence is not reasonably required for resolving any particular issue, it is difficult to see how it could ever be reasonably required for resolving the proceedings. I therefore see a test directed at issues as a filter".